Lubricating Compositions Containing Sulphonates and Phenates

ABSTRACT

A lubricating composition containing (a). at least 3 weight percent of an overbased sulphonate detergent with a metal ratio of 12.5:1 to 40:1; (b). at least 1.5 weight percent of a sulphur containing phenate detergent with a metal ratio of not more 2.5; and (c). an oil of lubricating viscosity, wherein the sulphur containing phenate contains oligomers of hydrocarbyl phenol with at least 50 wt % of said oligomers in the form of the tetramer or higher oligomers. The composition is suitable for internal combustion engines, particularly marine diesel applications to provide improved cleanliness decreased cylinder wear and reduced deposits.

FIELD OF INVENTION

The present invention relates to novel detergent compositions containing(a) at least 3 weight percent of an overbased sulphonate detergent witha metal ratio of 12.5:1 to 40:1; (b) at least 1.5 weight percent of asulphur containing phenate detergent with a metal ratio of not more than3; and (c) an oil of lubricating viscosity, wherein the sulphurcontaining phenate contains oligomers of hydrocarbyl phenol with atleast 50 wt % of said oligomers in the form of the tetramer or higheroligomers. The invention further relates to the use of the noveldetergent compositions in marine diesel cylinder lubricants.

BACKGROUND OF THE INVENTION

It is known to add various additives to an oil of lubricating viscosityfor diesel or gasoline engines to reduce wear and improve cleanliness.In diesel engines an oil of lubricating viscosity is used particularlyto reduce wear of cylinder liners and piston rings. Often engineoperating temperatures and pressures are sufficient to break down thefilm of the oil of lubricating viscosity on the internal walls of thecylinder. As a consequence of this, the cylinder experiences increasedwear and decreased engine cleanliness due to deposits. Formation of highlevels of deposits around the piston rings can also result in excessivewear.

U.S. Pat. No. 6,277,794, Dunn, discloses the use of a marine dieselengine lubricant composition containing (a) an overbased metal detergenthaving a TBN of at least 300 and/or (b) a metal detergent other thancomponent (a), provided that if detergent (b) is present the compositiondoes not contain a minor amount of an extreme pressure additive; and (c)ashless antiwear additives; and (d) an oil of lubricating viscosity.

U.S. Pat. No. 6,339,051, Carey et al., discloses diesel cylinder oilswith improved cleanliness and load carrying capabilities by using anadditive package containing at least one detergent, an antioxidant, anantiwear agent and a dispersant. The detergent component contains atleast one of an overbased phenate, phenylate, salicylate or sulphonate.

U.S. Pat. No. 6,376,434, Katafuchi, discloses lubricating oilcompositions for diesel engines containing at least one of (a) overbasedsulphonate, overbased phenates and overbased salicylates; and (b) abis-type succinic imide compound.

U.S. Pat. No. 6,551,965, Nagamatsu, discloses a marine diesellubricating oil composition containing an overbased alkyl sulphonatedetergent and an overbased sulphurised alkylphenate detergent. Theoverbased sulphurised alkylphenate has a TBN of 110 or more.

British Patent application GB 2,328,217A discloses marine diesellubricating oil compositions containing a polyalkylene succinimidecompound for improving anti-wear. The lubricating oil composition canfurther include up to 6% of at least one highly overbased detergentselected from alkyl or alkenyl phenates, alkyl or alkenylphenate-carboxylates, alkyl or alkenyl aromatic sulphonates; andmixtures thereof.

European Patent application EP 1,126,010 Nagamatsu et al., discloses alubricating oil composition containing an overbased alkylsulphonatedetergent and an overbased sulphurised phenate. The sulphurised phenateand overbased alkylsulphonate are present at on a weight ratio basis of55:45 to 95:5. The composition further includes a zinc antiwear agentsuch as dialkyldithiophosphate and a dispersant.

European Patent application EP 1,086,960 discloses a lubricating oilcomposition containing novel succinimide compounds and at least onedetergent selected from overbased sulphonates, phenates and salicylatesof alkaline earth metals.

East German Patent DD298519 discloses marine diesel engines employing ananticorrosion detergent-dispersant additive combination containing (a)weakly basic or neutral alkaline earth sulphonates; and (b) medium orhighly basic alkaline earth sulphonates, phenolates or phenolatesulphides in which the ratio of sulphonate groups to phenolic groups is1:3.6 to 4.4; and (c) a succinimide ash free detergent.

It would be desirable to have compositions with cleanliness properties.The invention provides compositions with cleanliness properties.

It would be desirable to have compositions capable of reducing wear andreducing deposits. The invention provides compositions capable ofreducing wear and reducing deposits.

SUMMARY OF THE INVENTION

The present invention provides a composition comprising:

(a) at least 3 weight percent of an overbased sulphonate detergent witha metal ratio of 12.5:1 to 40:1;

(b) at least 1.5 weight percent of a sulphur containing phenatedetergent with a metal ratio of not more than 3; and

(c) an oil of lubricating viscosity,

wherein the sulphur containing phenate contains oligomers of hydrocarbylphenol with at least 50 wt % of said oligomers in the form of thetetramer or higher oligomers.

The invention further provides a composition comprising:

(a). at least 3 weight percent of an overbased sulphonate detergent witha metal ratio of 12.5:1 to 40:1;

(b). at least 1.5 weight percent of a sulphur containing phenatedetergent with a metal ratio of not more than 3;

(c). an oil of lubricating viscosity, and

(d). an antiwear agent selected from the group consisting ofsalixarates, fatty amides, amine salts of phosphoric acid esters,thiocarbamate esters, thiocarbamates amides, thiocarbamic ethers,alkylene-coupled thiocarbamates, bis(S-alkyldithocarbamyl)disulfides,monoesters of polyols and aliphatic carboxylic acids, and borate esters;

wherein the sulphur containing phenate contains oligomers of hydrocarbylphenol with at least 50 wt % of said oligomers in the form of thetetramer or higher oligomers.

The invention further provides a process to prepare a compositioncomprising mixing:

(a) at least 3 weight percent of an overbased sulphonate detergent witha metal ratio of 12.5:1 to 40:1;

(b) at least 1.5 weight percent of a sulphur containing phenatedetergent with a metal ratio of not more than 3; and

(c) an oil of lubricating viscosity,

wherein the sulphur containing phenate contains oligomers of hydrocarbylphenol with at least 50 wt % of said oligomers in the form of thetetramer or higher oligomers.

The invention further provides a method for lubricating an internalcombustion engine, comprising supplying thereto a lubricant comprisingthe composition as described herein.

The invention further provides a composition with cleanlinessproperties. The invention further provides a composition capable ofreducing wear and capable of reducing deposits.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides, in certain embodiments, a compositioncomprising:

(a) at least 3 weight percent of an overbased sulphonate detergent witha metal ratio of 12.5:1 to 40:1;

(b) at least 1.5 weight percent of a sulphur containing phenatedetergent with a metal ratio of not more than 3; and

(c) an oil of lubricating viscosity,

wherein the sulphur containing phenate contains oligomers of hydrocarbylphenol with at least 50 wt % of said oligomers in the form of thetetramer or higher oligomers.

The total amount of (a) and (b) present on an oil free basis is oftenfrom 4.5 wt % to 35 wt %, in one aspect 6.5 wt % to 32 wt %, in anotheraspect 9 wt % to 30 wt % and in yet another aspect 12 wt % to 28 wt % ofthe composition. In one embodiment the weight percent of component (a)is 94.7 wt % and component (b) is 5.3 wt % of the total amount of (a)and (b) present. In one embodiment the amount of component (a) is 75 wt% and component (b) is 25 wt % of the total amount of (a) and (b)present.

Often the total base number (TBN) of the composition is 30 or higher, inone aspect 40 or higher, in another aspect 50 or higher and in yetanother aspect 60 or higher. In one embodiment, the specific amounts ofcomponent (a) and component (b) are present such that component (a)delivers at least 50%, in another embodiment at least 55%, in anotherembodiment at least 60, in another embodiment at least 65 and in yetanother embodiment at least 70% of the TBN supplied by the detergents(a) and (b).

In one embodiment the weight percent ratio of overbased sulphonate tosulphur containing phenate detergent is often 30:1 to 0.85:1, in oneaspect 25:1 to 0.9:1, in another aspect 20:1 to 0.95:1, in yet anotheraspect 20:1 to 1:1 and in yet another aspect 20:1 to 1.02:1. Inembodiment the weight percent ratio of overbased sulphonate to sulphurcontaining phenate detergent is 15:1 to 1.05:1, in another embodiment10:1 to 1.05:1 and in another embodiment 10:1 to 1.1:1.

Overbased Sulphonate Detergent

The sulphonate detergent of the composition may be represented by theformula:

(R¹)_(k)-A-SO₃M  (I)

wherein each R¹ is independently an alkyl, cycloalkyl, aryl, acyl, orother hydrocarbyl group with 6 to 40, in one aspect 8 to 25 and inanother aspect 9 to 20 carbon atoms; A may be independently a cyclic oracyclic hydrocarbon group; M is hydrogen, a valence of a metal ion, anammonium ion or mixtures thereof; and k is an integer of 0 to 5, forexample 0, 1, 2, 3, 4, 5. In one aspect k is 1, 2 or 3, in anotheraspect 1 or 2 and in yet another aspect 1. Often hydrogen comprises lessthan 30%, in one aspect less than 20%, in another aspect less than 10%and in yet another aspect less than 5% of the available M entities.

In one embodiment k is 1 and R¹ is a branched alkyl group with 6 to 40carbon atoms. In one embodiment k is 1 and R¹ is a linear alkyl groupwith 6 to 40 carbon atoms.

Examples of suitable sulphonic acids capable of forming the overbasedsulphonate detergent include polypropene benzene sulphonic acid, undecylbenzene sulphonic acid, dodecyl benzene sulphonic acid, tridecyl benzenesulphonic acid, tetradecyl benzene sulphonic acid, pentadecyl benzenesulphonic acid, hexadecyl benzene sulphonic acid and mixtures thereof.In one embodiment the sulphonic acid includes undecyl benzene sulphonicacid, dodecyl benzene sulphonic acid, tridecyl benzene sulphonic acid,tetradecyl benzene sulphonic acid, octadecyl benzene sulphonic acid,tetraeicosyl benzene sulphonic acid or mixtures thereof. In oneembodiment of the invention the sulphonic acid is a polypropene benzenesulphonic acid, where the polypropene is often derived from 18 to 30carbon atoms.

In one embodiment of the invention the sulphonate components are calciumpolypropene benzenesulphonate and calcium monoalkyl and dialkylbenzenesulphonates wherein the alkyl groups contain at least 10 carbons,for example 11, 12, 13, 14, or 15 carbon atoms.

When M is a valence of a metal ion, the metal may be monovalent,divalent, trivalent or mixtures of such metals. When monovalent, themetal M may be an alkali metal, in one aspect lithium, sodium, orpotassium; and in another aspect potassium, which may be used alone orin combination with other metals. When divalent, the metal M may be analkaline earth metal, in one aspect magnesium, calcium, barium ormixtures of such metals, in another aspect calcium, which may be usedalone or in combination with other metals. When trivalent, the metal Mmay be aluminium, which may be used alone or in combination with othermetals. In one embodiment the metal is an alkaline earth metal. In oneembodiment the metal is calcium.

When A is cyclic hydrocarbon group, suitable groups include phenyl orfused bicyclic groups such as naphthalene, indenyl, indanyl,bicyclopentadienyl and mixtures thereof. Although A may be a fusedbicyclic ring, benzene rings are often especially useful.

When A is an acyclic hydrocarbon group, the carbon chain may be linearor branched, although linear is especially useful. Suitable groupsinclude derivatives of carboxylic acids containing 7 to 30, in oneaspect 7 to 20, in another aspect 8 to 20 and in yet another aspect 8 to15 carbon atoms. Further the chain may be saturated or unsaturated,although saturated is especially useful.

Typically the overbased sulphonate detergent has a TBN (total basenumber) of at least 400, in one aspect at least 425, in another aspectat least 450 and in yet another aspect at least 475. In one embodimentthe overbased sulphonate detergent has a TBN of 500, or of 500 to 550.

Overbasing the Sulphonate Detergent

The sulphonate detergent is overbased. Overbased materials, otherwisereferred to as overbased or superbased salts, are generally singlephase, homogeneous Newtonian systems characterised by a metal content inexcess of that which would be necessary for neutralisation according tothe stoichiometry of the metal and the particular acidic organiccompound reacted with the metal. The overbased materials are prepared byreacting an acidic material (typically an inorganic acid or lowercarboxylic acid, often carbon dioxide) with a mixture comprising anacidic organic compound, a reaction medium comprising at least oneorganic solvent and promoter such as phenol or a mixture of alcohols. Amixture of alcohols typically contains methanol and at least one alcoholwith 2 to 7 carbon atoms, and may contain 50-60 mole percent methanol.The acidic material will normally have a sufficient number of carbonatoms to provide a degree of solubility in oil. The amount of excessmetal is commonly expressed in terms of substrate to metal ratio. Theterm “substrate to metal ratio” is the ratio of the total equivalents ofthe metal to the equivalents of the substrate. An overbased sulphonatedetergent typically has a metal ratio of 12.5:1 to 40:1, in one aspect13.5:1 to 40:1, in another aspect 14.5:1 to 40:1, in yet another aspect15.5:1 to 40:1 and in yet another aspect 16.5:1 to 40:1. Furthermore theoverbased detergent often has a low in-process viscosity and a low finalviscosity.

A sulphonate detergent with 500 TBN and its preparation are disclosed inU.S. Pat. No. 5,792,732. In Example 2 thereof, a 500 TBN all-linearalkylbenzene sulphonate is prepared by reacting an alkyl benzenesulphonate from Witco Corp. (now known as Crompton) with Ca(OH)₂ and CaOin n-heptane and methanol and bubbling with CO₂. It is also reported inthe aforementioned patent (col. 5) that a 500 TBN overbased sulphonatecontaining highly branched alkylbenzene sulphonate is available fromWitco Corp. (now known as Crompton) as Petronate® C-500. Another methodfor preparing an overbased sulfonate detergent of high metal ratio isdisclosed in U.S. Pat. No. 6,444,625 (see, for instance, column 3,bottom). The latter process includes providing a sulfonic acid to areactor, adding a lime reactant for neutralization and overbasing,adding a lower aliphatic C₁ to C₄ alcohol and a hydrocarbon solvent, andcarbonating the process mixture with carbon dioxide during which processthe exotherm of the reaction is maintained between 27° C. and 57° C.Alternatively, a high metal-ratio detergent may be prepared by using amixture of short chain alcohols, with or without a hydrocarbon solvent,conducting the addition of lime reactants and carbon dioxide in multipleiterations, and, if desired the process of adding lime and carbondioxide and of removal of volatile materials may be repeated. Theoverbased sulphonate detergent in the present invention may be usedalone or with other overbased sulphonates. In one embodiment thesulphonate detergent is in a mixture with other sulphonate detergents,provided the TBN is within the given ranges.

Sulphur Containing Phenate Detergent

The sulphur containing phenate detergent of the composition may berepresented by the formula:

wherein the number of sulphur atoms y may be in the range from 1 to 8,in one aspect 1 to 6 and in another aspect 1 to 4; R² may be hydrogen orhydrocarbyl groups; T is hydrogen or an (S)_(y) linkage terminating inhydrogen, an ion or a non-phenolic hydrocarbyl group; and M is asdescribed above.

The monomeric units of structure (II) combine in such a way with itselfx number of times to form oligomers of hydrocarbyl phenol. Oligomers aredescribed as dimers, trimers, tetramers, pentamers and hexamers when xis equal to 0, 1, 2, 3, and 4, respectively. Typically the number ofmonomers represented by x may be 0 to 10, in one aspect 1 to 9, inanother aspect 1 to 8, in yet another aspect 2 to 6 and in yet anotheraspect 2 to 5. Typically an oligomer is present in significantquantities if concentrations are above 0.1 wt %, in one aspect above 1wt % and in another aspect above 2 wt %. Typically an oligomer ispresent in trace amounts if concentrations are less than 0.1 wt %, forexample, oligomers with 11 or more repeat units may be present.Generally in at least 50% of the molecules, x is 2 or higher. In oneembodiment of the invention the overall sulphur-containing phenatedetergent contains less than 20 wt. % dimeric structures (x=0).

The sulphur containing phenate detergent contains oligomers ofhydrocarbyl phenol with at least 50 wt % in the form of the tetramer orhigher oligomers. Often the tetramer or higher oligomers are present inamounts of at least 52 wt %, in one aspect at least 54 wt %, in anotheraspect at least 56 wt % and in yet another aspect at least 58 wt %.

The sulphur containing phenate detergent often contains less than 20 wt%, in one aspect less than 18 wt %, in another aspect less than 16 wt %and in yet another aspect less than 14 wt % of hydrocarbyl phenoldimers.

The sulphur containing phenate detergent often contains a substratelevel (that is, excluding M and any carbonate of M) in the range 45 wt %to 95 wt %, in one aspect 50 wt % to 90 wt % and in another aspect 55 wt% to 85, to 80, or to 75 wt % of the sulphur containing phenatedetergent. The “substrate” means the anionic portion of Structure II orsimilar structures. The substrate level is calculated excluding anycontribution of diluent oil to the detergent.

In Structure II, each R² may be hydrogen or a hydrocarbyl groupcontaining 4 to 80, in one aspect 6 to 45, in another aspect 8 to 20 andin yet another aspect 9 to 14 carbon atoms. The number of R²substituents (w) other than hydrogen on each aromatic ring may be 0 to4, in one aspect 1 to 3 and in another aspect 1 to 2. Where two or morehydrocarbyl groups are present they may be the same or different; andthe minimum total number of carbon atoms present in the hydrocarbylsubstituents on all the rings, to ensure oil solubility, may be 8 or inone aspect 9. Especially useful components include 4-alkylated phenolscontaining alkyl groups with the number of carbon atoms of 9 to 14, forexample 9, 10, 11, 12, 13, 14 and mixtures thereof. The 4-alkylatedphenols typically contain sulphur at position 2.

Typically the sulphur containing phenate detergent has a TBN from 30 to220, in one aspect 40 to 205, in another aspect 50 to 190 and in yetanother aspect 70 to 175. In one embodiment the sulphur containingphenate detergent has a TBN of 150. The sulphur containing phenatedetergent may be used alone or with other sulphur containing phenatedetergents. In one embodiment the sulphur containing phenate detergentis in a mixture with other phenate detergents, provided the TBN of theaverage of all the phenates is within the given ranges.

The sulphur containing phenate detergent typically has a metal ratio ofnot more than 3, in one aspect not more than 2.7, in another aspect notmore than 2.5, in yet another aspect not more than 2.3 and in yetanother aspect not more than 2.1.

The sulphur containing phenate further contains oligomers of hydrocarbylphenol with at least 50 wt % of such oligomers being in the form of thetetramer or higher oligomers. A suitable example of calcium alkyl phenolsulphide detergent is commercially available from The LubrizolCorporation.

Oils of Lubricating Viscosity

The invention further includes oil of lubricating viscosity. Such oilsinclude natural and synthetic oils, oil derived from hydrocracking,hydrogenation, and hydrofinishing, unrefined, refined and re-refinedoils and mixtures thereof.

Unrefined oils are those obtained directly from a natural or syntheticsource generally without (or with little) further purificationtreatment.

Refined oils are similar to the unrefined oils except they have beenfurther treated in one or more purification steps to improve one or moreproperties. Purification techniques are known in the art and includesolvent extraction, secondary distillation, acid or base extraction,filtration, percolation and the like.

Re-refined oils are also known as reclaimed or reprocessed oils, and areobtained by processes similar to those used to obtain refined oils andoften are additionally processed by techniques directed to removal ofspent additives and oil breakdown products.

Natural oils useful in making the inventive lubricants include animaloils, vegetable oils (e.g., castor oil, lard oil), mineral lubricatingoils such as liquid petroleum oils and solvent-treated or acid-treatedmineral lubricating oils of the paraffinic, naphthenic or mixedparaffinic-naphthenic types and oils derived from coal or shale ormixtures thereof.

Synthetic lubricating oils are useful and include hydrocarbon oils suchas polymerised and interpolymerised olefins (e.g., polybutylenes,polypropylenes, propyleneisobutylene copolymers); poly(1-hexenes),poly(1-octenes), poly(1-decenes), and mixtures thereof; alkyl-benzenes(e.g. dodecylbenzenes, tetradecylbenzenes, dinonylbenzenes,di-(2-ethylhexyl)-benzenes); polyphenyls (e.g., biphenyls, terphenyls,alkylated polyphenyls); alkylated diphenyl ethers and alkylated diphenylsulphides and the derivatives, analogs and homologs thereof or mixturesthereof.

Other synthetic lubricating oils include but are not limited to liquidesters of phosphorus-containing acids (e.g., tricresyl phosphate,trioctyl phosphate, and the diethyl ester of decane phosphonic acid),and polymeric tetrahydrofurans. Synthetic oils may be produced byFischer-Tropsch reactions and typically may be hydroisomerisedFischer-Tropsch hydrocarbons or waxes.

Oils of lubricating viscosity may also be defined as specified in theAmerican Petroleum Institute (API) Base Oil InterchangeabilityGuidelines. The five base oil groups are as follows: Group I (sulphurcontent>0.03 wt %, and/or <90 wt % saturates, viscosity index 80-120);Group II (sulphur content≦0.03 wt %, and ≧90 wt % saturates, viscosityindex 80-120); Group III (sulphur content≦0.03 wt %, and ≧90 wt %saturates, viscosity index≧120); Group IV (all polyalphaolefins (PAOs));and Group V (all others not included in Groups I, II, III, or IV). Theoil of lubricating viscosity comprises an API Group I, Group II, GroupIII, Group IV, Group V oil and mixtures thereof. Often the oil oflubricating viscosity is an API Group I, Group II, Group III, Group IVoil and mixtures thereof. Alternatively the oil of lubricating viscosityis often an API Group I, Group II, Group III oil or mixtures thereof.

The oil of lubricating viscosity is often present at 55 to 99.9, in oneaspect 61 to 98.9, in another aspect 65 to 96.8 and in yet anotheraspect 67 to 94 weight percent of the composition.

Other Performance Additives

Optionally the composition may include at least one performance additiveother than components (a)-(c), selected from the group consisting ofmetal deactivators, detergents, dispersant, antioxidants, antiwearagents, corrosion inhibitors, antiscuffing agents, extreme pressureagents, foam inhibitors, demulsifiers, friction modifiers, viscositymodifiers, pour point depressants and mixtures thereof. Typically,fully-formulated lubricating oil will contain one or more of theseperformance additives. In some embodiments, certain antiwear agents arepresent as component (d).

In one embodiment of the invention the composition contains at least oneoptional performance additive selected from the group consisting of adispersant, an antioxidant and an antiwear agent.

The total combined amount of the other performance additives present onan oil free basis may be 0 to 10, in one aspect 0.1 to 7, in anotheraspect 0.2 to 5 and in yet another aspect 1 to 5 weight percent of thecomposition.

Dispersants

Dispersants are often known as ashless-type dispersants because, priorto mixing in a lubricating oil composition, they do not containash-forming metals and they do not normally contribute any ash formingmetals when added to a lubricant and polymeric dispersants. Ashless typedispersants are characterised by a polar group attached to a relativelyhigh molecular weight hydrocarbon chain. Typical ashless dispersantsinclude N-substituted long chain alkenyl succinimides. Examples ofN-substituted long chain alkenyl succinimides include polyisobutylenesuccinimide with number average molecular weight of the polyisobutylenesubstituent in the range 350 to 5000, in one aspect 500 to 3000.Succinimide dispersants and their preparation are disclosed, forinstance in U.S. Pat. No. 4,234,435. Succinimide dispersants aretypically the imide formed from a polyamine, typically apoly(ethyleneamine).

In one embodiment the invention further comprises at least onedispersant derived from polyisobutylene succinimide with number averagemolecular weight in the range 350 to 5000, in one aspect 500 to 3000.The polyisobutylene succinimide may be used alone or in combination withother dispersants.

In one embodiment the invention further comprises at least onedispersant derived from polyisobutylene, an amine and zinc oxide to forma polyisobutylene succinimide complex with zinc. The polyisobutylenesuccinimide complex with zinc may be used alone or in combination.

Another class of ashless dispersant is Mannich bases. Mannichdispersants are the reaction products of alkyl phenols with aldehydes(especially formaldehyde) and amines (especially polyalkylenepolyamines). The alkyl group typically contains at least 30 carbonatoms.

The dispersants may also be post-treated by conventional methods by areaction with any of a variety of agents. Among these are urea,thiourea, dimercaptothiadiazoles, carbon disulfide, aldehydes, ketones,carboxylic acids, hydrocarbon-substituted succinic anhydrides, maleicanhydride, nitriles, epoxides, boron compounds, and phosphoruscompounds.

In one embodiment of the invention the dispersant is borated using avariety of agents selected from the group consisting of the variousforms of boric acid (including metaboric acid, HBO₂, orthoboric acid,H₃BO₃, and tetraboric acid, H₂B₄O₇), boric oxide, boron trioxide, andalkyl borates. In one embodiment the borating agent is boric acid whichmay be used alone or in combination with other borating agents.

The borated dispersant may be prepared by blending the boron compoundand the N-substituted long chain alkenyl succinimides and heating themat a suitable temperature, typically 80° C. to 250° C., in one aspect90° C. to 230° C. and in another aspect 100° C. to 210° C., until thedesired reaction has occurred. The molar ratio of the boron compounds tothe N-substituted long chain alkenyl succinimides is typically 10:1 to1:4, in one aspect 4:1 to 1:3, and in another aspect 1:2. An inertliquid may be used in performing the reaction. The liquid may includetoluene, xylene, chlorobenzene, dimethylformamide and mixtures thereof.

Often the dispersant is present on an oil free basis at 0 to 10, in oneaspect 0.01 to 5, in another aspect 0.02 to 2 and in yet another aspect0.05 or 0.1 to 1 weight percent of the composition.

Detergents

Detergents, in addition to those described above as components (a) and(b), are known and may include neutral or overbased, Newtonian ornon-Newtonian, basic salts of alkali, alkaline earth and transitionmetals with one or more hydrocarbyl sulphonic acid, carboxylic acid,phosphorus acid, mono- and/or di-thiophosphoric acid, alkyl phenol,sulphur coupled alkyl phenol compounds, salixarates, saligenins ormixtures thereof. Commonly used metals include sodium, potassium,calcium, magnesium lithium or mixtures thereof. Most commonly usedmetals include sodium, magnesium, calcium or mixtures thereof.Detergents and in particular overbased detergents and their preparationare disclosed in U.S. Pat. No. 3,629,109.

Antioxidant

Antioxidant compounds are known and include a diphenylamine, a hinderedphenol, a molybdenum dithiocarbamate, a sulphurised olefin and mixturesthereof. Antioxidant compounds may be used alone or in combination.

The diphenylamine antioxidant may be represented by the formula:

wherein R³ and R⁴ may be a hydrocarbyl groups, often arylalkyl or alkylgroups. The arylalkyl groups may contain 6 to 20 and in another aspect 6to 10 carbons atoms. The alkyl groups may be linear or branched,especially linear; the alkyl groups may contain 1 to 24, in one aspect 2to 18 and in another aspect 4 to 12 carbon atoms; and z is independently0, 1, 2, or 3, provided that at least one aromatic ring contains ahydrocarbyl group. Especially useful alkylated diphenylamines includeoctyl diphenylamine, nonyl diphenylamine, bis-octyl diphenylamine andbis-nonyl diphenylamine.

The hindered phenol antioxidant often contains a secondary butyl and/ora tertiary butyl group as a sterically hindering group. The phenol groupis often further substituted with a hydrocarbyl group and/or a bridginggroup linking to a second aromatic group. Examples of suitable hinderedphenol antioxidants include 2,6-di-tert-butylphenol,4-methyl-2,6-di-tert-butylphenol, 4-ethyl-2,6-di-tert-butylphenol,4-propyl-2,6-di-tert-butylphenol or 4-butyl-2,6-di-tert-butylphenol2,6-di-tert-butylphenol. In one embodiment the hindered phenolantioxidant is an ester and may include, e.g., Irganox™ L-135 from Ciba.A more detailed description of suitable ester-containing hindered phenolantioxidant chemistry is found in U.S. Pat. No. 6,559,105.

Suitable examples of molybdenum dithiocarbamates which may be used as anantioxidant include commercial materials sold under the trade names suchas Vanlube 822™ and Molyvan™ A from R. T. Vanderbilt Co., Ltd., andAdeka Sakura-Lube™ S-100, S-165 and S-600 from Asahi Denka Kogyo K. Kand mixtures thereof.

Examples of suitable olefins that may be sulphurised to form anantioxidant include propylene, butylene, isobutylene, pentene, hexane,heptene, octane, nonene, decene, undecene, dodecene, undecyl, tridecene,tetradecene, pentadecene, hexadecene, heptadecene, octadecene,octadecenene, nonodecene, eicosene or mixtures thereof. In oneembodiment, hexadecene, heptadecene, octadecene, octadecenene,nonodecene, eicosene or mixtures thereof and their dimers, trimers andtetramers are especially useful olefins. Alternatively, the olefin maybe a Diels-Alder adduct of a diene such as 1,3-butadiene and anunsaturated ester such as butyl(meth)acrylate.

Another class of sulphurised olefin includes fatty acids and theiresters. The fatty acids are often obtained from vegetable oil or animaloil; and typically contain 4 to 22 carbon atoms. Examples of suitablefatty acids and their esters include triglycerides, oleic acid, linoleicacid, palmitoleic acid or mixtures thereof. Often, the fatty acids areobtained from lard oil, tall oil, peanut oil, soybean oil, cottonseedoil, sunflower seed oil or mixtures thereof. In one embodiment fattyacids and/or ester are mixed with olefins. Sulphurised olefins may alsoprovide extreme pressure performance and antiwear functionality to thecomposition.

Often an antioxidant is present on an oil free basis at 0 to 10, in oneaspect 0.01 to 5, in another aspect 0.02 to 2 and in yet another aspect0.03 to 1 weight percent of the composition.

Antiwear Agent

In certain embodiments of the invention the composition further contains(d) an antiwear agent such as a metal hydrocarbyl dithiophosphate oftenrepresented by the formula:

wherein R⁵ and R⁶ are independently hydrogen, hydrocarbyl groups ormixtures thereof, provided that at least one of R⁵ and R⁶ is ahydrocarbyl group, in one aspect alkyl or cycloalkyl with 2 to 30, inone aspect 3 to 10 and in yet another aspect 3 to 8 carbon atoms.

M′ is a metal, and n is an integer equal to the available valence of M′.M′ is mono- or di- or tri-valent, in one aspect divalent and in anotheraspect a divalent transition metal. In one embodiment M′ is zinc. In oneembodiment M′ is calcium. In one embodiment M′ is barium. Examples of ametal hydrocarbyl dithiophosphate include zinc dihydrocarbyldithiophosphates (often referred to as ZDDP, ZDP or ZDTP). Examples ofsuitable zinc hydrocarbyl dithiophosphates compounds may include thereaction product(s) of heptylated or octylated or nonylateddithiophosphoric acids with ethylene diamine, morpholine or mixturesthereof.

In one embodiment, the antiwear agent is a salixarate detergent. Thesematerials, which are also known as salts of linear (or cyclic) compoundscontaining phenolic and salicylic units, condensed with an aldehyde suchas formaldehyde, are known from US Patent Publication 2004/0186027. Itis also known from this same document that these materials are usefulboth for their detergent properties and as antiwear agents. Salixaratedetergents are also described in copending U.S. application Ser. No.10/751,809 filed 5 Jan. 2004

In an alternative embodiment the antiwear agent is ashless i.e. theantiwear agent is metal-free. Often the metal-free antiwear agent is anamine salt, for instance, a fatty amine salt of a phosphoric acid ester.The ashless antiwear agent often contains an atom including sulphur,phosphorus, boron or mixtures thereof.

Suitable hydrocarbyl amine salts of alkylphosphoric acid (which term isintended to include alkylthiophosphoric acid) may be represented by thefollowing formulas:

wherein R²¹ and R²² are independently hydrogen or hydrocarbyl groupssuch as alkyl groups; for the phosphorus acid ester, at least one of R²¹and R²² will be hydrocarbyl. R²¹ and R²² may contain 4 to 30, or 8 to25, or 10 to about 20, or 13 to 19 carbon atoms. R²³, R²⁴ and R²⁵ can beindependently hydrogen or hydrocarbyl groups, such as alkyl branched orlinear alkyl chains with 1 to 30, or 4 to 24, or 6 to 20, or 10 to 16carbon atoms. These R²³, R²⁴ and R²⁵ groups can be branched or lineargroups, and in certain embodiments at least one, or alternatively two ofR²³, R²⁴ and R²⁵ are hydrogen. Examples of alkyl groups suitable forR²³, R²⁴ and R²⁵ include butyl, sec-butyl, isobutyl, tert-butyl, pentyl,n-hexyl, sec-hexyl, n-octyl, 2-ethylhexyl, decyl, undecyl, dodecyl,tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl,octadecenyl, nonodecyl, eicosyl groups and mixtures thereof. In oneembodiment the hydrocarbyl amine salt of an alkylphosphoric acid estercan be the reaction product of a C₁₄ to C₁₈ alkylated phosphoric acidwith Primene 81R™ (produced and sold by Rohm & Haas) which is a mixtureof C₁₁ to C₁₄ tertiary alkyl primary amines.

The amine is often a primary amine, a secondary amine a tertiary amineor mixtures thereof. Often a primary amine and/or a secondary amine willcontain at least one hydrocarbyl group with the number of carbon atomspresent from 2 to 30, in one aspect 8 to in one aspect 26, in anotheraspect 10 to 20, and in yet another aspect 11 to 18.

Examples of primary amines useful in the present invention includeethylamine, propylamine, butylamine, 2-ethylhexylamine, octylamine anddodecylamine. Also suitable primary fatty amines which includen-octylamine, n-decylamine, n-dodecylamine, n-tetradecylamine,n-hexadecylamine, noctadecylamine and oleyamine. Other useful fattyamines include commercially available fatty amines such as “Armeen®”amines (products available from Akzo Chemicals, Chicago, Ill.), such asArmeen C, Armeen O, Armeen OL, Armeen T, Armeen HT, Armeen S and ArmeenSD, wherein the letter designation relates to the fatty group, such ascoco, oleyl, tallow, or stearyl groups.

Examples of suitable secondary amines include dimethylamine,diethylamine, dipropylamine, dibutylamine, diamylamine, dihexylamine,diheptylamine, methylethylamine, ethylbutylamine and ethylamylamine. Thesecondary amines may be cyclic amines such as piperidine, piperazine andmorpholine.

The amine may also be a tertiary-aliphatic primary amine. Often thealiphatic group is an alkyl group containing a number of carbon atomsfrom 2 to 30, in one aspect 6 to 26 and in another aspect 8 to 24. Oftenthe tertiary alkyl primary amines are monoamines such astert-butylamine, terthexylamine, 1-methyl-1-amino-cyclohexane,tert-octyl amine, tert-decyl amine, tertdodecylamine,tert-tetradecylamine, tert-hexadecylamine, tert-octadecylamine,terttetracosanylamine, and tert-octacosanylamine.

Mixtures of amines may also be used in the invention. Especially usefulmixtures of amines are “Primene 81R” and “Primene JMT.” Primene 81R andPrimene JMT (both produced and sold by Rohm & Haas) are mixtures of C₁₁to C₁₄ tertiary alkyl primary amines and C₁₋₈ to C₂₂ tertiary alkylprimary amines respectively.

The ashless antiwear agent may also include phosphoric acid esters orsalts thereof; dialkyldithiophosphoric acid esters or salts thereof;phosphites; and phosphorus-containing carboxylic esters, ethers, andamides or mixtures thereof.

Other Ashless antiwear agent compounds include sulphur-containingashless anti-wear additives such as thiocarbamate-containing compounds,such as thiocarbamate esters, thiocarbamate amides, thiocarbamic ethers,alkylene-coupled thiocarbamates, and bis(S-alkyldithiocarbamyl)disulfides.

The dithiocarbamate-containing compounds may be prepared by reacting adithiocarbamate acid or salt with an unsaturated compound. Thedithiocarbamate containing compounds may also be prepared bysimultaneously reacting an amine, carbon disulfide and an unsaturatedcompound. Generally, the reaction occurs at a temperature from 25° C. to125° C. U.S. Pat. Nos. 4,758,362 and 4,997,969 describe dithiocarbamatecompounds and methods of making them.

Useful fatty amines include commercially available fatty amines such as“Armeen”® amines (products available from Akzo Chemicals, Chicago,Ill.), such as Akzo's, Armeen C, Armeen O, Armeen OL, Armeen T, ArmeenHT, Armeen S and Armeen SD, wherein the letter designation relates tothe fatty group, such as coco, oleyl, tallow, or stearyl groups.

In an alternative embodiment of the invention, the ashless antiwearagent may be a monoester of a polyol and an aliphatic carboxylic acid,often an acid containing 12 to 24 carbon atoms. Often the monoester of apolyol and an aliphatic carboxylic acid is in the form of a mixture witha sunflower oil or the like, which may be present in the frictionmodifier mixture from 5 to 95, in one aspect 10 to 90, in another aspect20 to 85 and in yet another aspect 20 to 80 weight percent of saidmixture. The aliphatic carboxylic acids (especially a monocarboxylicacid) which form the esters are those acids containing 12 to 24 carbonatoms and in one aspect 14 to 20 carbon atoms. Examples of carboxylicacids include dodecanoic acid, stearic acid, lauric acid, behenic acid,and oleic acid.

Polyols include diols, triols, and alcohols with higher numbers ofalcoholic OH groups. Polyhydric alcohols include ethylene glycols,including di-, tri- and tetraethylene glycols; propylene glycols,including di-, tri- and tetrapropylene glycols; glycerol; butane diol;hexane diol; sorbitol; arabitol; mannitol; sucrose; fructose; glucose;cyclohexane diol; erythritol; and pentaerythritols, including di- andtripentaerythritol. Often the polyol is diethylene glycol, triethyleneglycol, glycerol, sorbitol, pentaerythritol or dipentaerythritol.

The commercially available monoester known as “glycerol monooleate” isbelieved to include 60±5 percent by weight of the chemical speciesglycerol monooleate, along with 35±5 percent glycerol dioleate, and lessthan 5 percent trioleate and oleic acid. The amounts of the monoesters,described above, are calculated based on the actual, corrected, amountof polyol monoester present in any such mixture.

In one embodiment of the invention the antiwear agent is a borate ester.The borate ester may be prepared by the reaction of a boron compound andat least one compound selected from epoxy compounds, halohydrincompounds, epihalohydrin compounds, alcohols and mixtures thereof.Typically the alcohols include monohydric alcohols, dihydric alcohols,trihydric alcohols or higher alcohols.

Boron compounds suitable for preparing the borate ester include a boricacid (including metaboric acid, HBO₂, orthoboric acid, H₃BO₃, and atetraboric acid, H₂B₄O₇), a boric oxide, a boron trioxide and an alkylborate. The borate ester may also be prepared from boron halides. Theborated ester further contains at least one hydrocarbyl group oftencontaining about 8 to about 30 carbon atoms.

In another embodiment the antiwear agent can be a fatty amide. This canbe an amide based on the condensation of a fatty amine as describedabove with a carboxylic acid, or the condensation of a fatty acid withammonia or an amine. An illustrative fatty amide is oleamide.

Often the antiwear agent is present on an oil free basis from 0 to 10,in one aspect 0.01 to 5, in another aspect 0.02 to 2 and in yet anotheraspect 0.05 to 1 weight percent of the composition. The antiwear agentmay be used alone or in combination.

Antiscuffing Agent

The lubricant may also contain an antiscuffing agent. Antiscuffing agentcompounds are believed to decrease adhesive wear are often sulphurcontaining compounds. Typically the sulphur containing compounds includeorganic sulphides and polysulphides, such as dibenzyldisulphide,bis(chlorobenzyl) disulphide, dibutyl tetrasulphide, di-tertiary butylpolysulphide, sulphurised methyl ester of oleic acid, sulphurisedalkylphenol, sulphurised dipentene, sulphurised terpene, sulphurisedDiels-Alder adducts, alkyl sulphenyl N′N-dialkyl dithiocarbamates, thereaction product of polyamines with polybasic acid esters, chlorobutylesters of 2,3-dibromopropoxyisobutyric acid, acetoxymethyl esters ofdialkyl dithiocarbamic acid and acyloxyalkyl ethers of xanthogenic acidsand mixtures thereof.

Extreme Pressure Agents

Extreme Pressure (EP) agents that are soluble in the oil includesulphur- and chlorosulphur-containing EP agents, chlorinated hydrocarbonEP agents and phosphorus EP agents. Examples of such EP agents includechlorinated wax; organic sulphides and polysulphides such asdibenzyldisulphide, bis(chlorobenzyl) disulphide, dibutyl tetrasulphide,sulphurised methyl ester of oleic acid, sulphurised alkylphenol,sulphurised dipentene, sulphurised terpene, and sulphurised Diels-Alderadducts; phosphosulphurised hydrocarbons such as the reaction product ofphosphorus sulphide with turpentine or methyl oleate; phosphorus esterssuch as the dihydrocarbon and trihydrocarbon phosphites, e.g., dibutylphosphite, diheptyl phosphite, dicyclohexyl phosphite, pentylphenylphosphite; dipentylphenyl phosphite, tridecyl phosphite, distearylphosphite and polypropylene substituted phenol phosphite; metalthiocarbamates such as zinc dioctyldithiocarbamate and bariumheptylphenol diacid; the zinc salts of a phosphorodithioic acid; aminesalts of alkyl and dialkylphosphoric acids, including, for example, theamine salt of the reaction product of a dialkyldithiophosphoric acidwith propylene oxide; and mixtures thereof.

Other performance additives such as corrosion inhibitors includingoctylamine octanoate, condensation products of dodecenyl succinic acidor anhydride and a fatty acid such as oleic acid with a polyamine; metaldeactivators including derivatives of benzotriazoles, 1,2,4-triazoles,benzimidazoles, 2-alkyldithiobenzimidazoles or2-alkyldithiobenzothiazoles; foam inhibitors including copolymers ofethyl acrylate and 2-ethylhexylacrylate and optionally vinyl acetate;demulsifiers including trialkyl phosphates, polyethylene glycols,polyethylene oxides, polypropylene oxides and (ethylene oxide-propyleneoxide) polymers; pour point depressants including esters of maleicanhydride-styrene, polymethacrylates, polyacrylates or polyacrylamides;viscosity modifiers including styrene-butadiene rubbers,ethylene-propylene copolymers, hydrogenated styrene-isoprene polymers,hydrogenated radical isoprene polymers, poly(meth)acrylate acid esters,polyalkyl styrenes, polyolefins, polyalkylmethacrylates and esters ofmaleic anhydride-styrene copolymers; and friction modifiers includingfatty acid derivatives such as amines, esters, epoxides, fattyimidazolines, condensation products of carboxylic acids andpolyalkylenepolyamines and amine salts of alkylphosphoric acids may alsobe used in the composition of the invention.

Process

The invention also includes a process to prepare the composition of thepresent invention, comprising mixing:

(a) at least 3 weight percent of an overbased sulphonate detergent witha metal ratio of 12.5:1 to 40:1;

(b) at least 1.5 weight percent of a sulphur containing phenatedetergent with a metal ratio of not more than 3; and

(c) an oil of lubricating viscosity,

wherein the sulphur containing phenate contains oligomers of hydrocarbylphenol with at least 50 wt % of said oligomers in the form of thetetramer or higher oligomers.

If an additional component (d) such as an antiwear agent is present,such component can also be mixed with (a), (b), and (c), in any order.

The mixing conditions are typically 15° C. to 130° C., in one aspect 20°C. to 120° C. and in another aspect 25° C. to 110° C.; and for a periodof time in the range 30 seconds to 48 hours, in one aspect 2 minutes to24 hours, and in another aspect 5 minutes to 16 hours; and at pressuresin the range 86.4 kPa to 266 kPa (650 mm Hg to 2000 mm Hg), in oneaspect 91.8 kPa to 200 kPa (690 mm Hg to 1500 mm Hg), and in anotheraspect 95.1 kPa to 133 kPa (715 mm Hg to 1000 mm Hg).

The process optionally includes mixing other performance additives asdescribed above. The optional performance additives may be addedsequentially, separately or as a concentrate.

If the present invention is in the form of a concentrate (which may becombined with additional oil to form, in whole or in part, a finishedlubricant), the ratio of each of the above-mentioned dispersant, as wellas other components, to diluent oil is typically in the range of 80:20to 10:90 by weight.

INDUSTRIAL APPLICATION

The compositions of the present invention are useful as detergents in aninternal combustion engines, for example diesel fuelled engines,gasoline fuelled engines, natural gas fuelled engines or a mixedgasoline/alcohol fuelled engines.

In one embodiment of the invention provides a method for lubricating aninternal combustion engine, comprising supplying thereto a lubricantcomprising the composition as described herein. The invention issuitable for 2-stroke or 4-stroke marine diesel engines, especially2-stroke engines. The use of the composition may impart one or more ofimproved cleanliness, reduced wear (especially cylinder wear) andreduced deposits.

The following examples provide an illustration of the invention. Theseexamples are non exhaustive and are not intended to limit the scope ofthe invention.

EXAMPLES Preparative Example 1 Formation of 500 TBN Sulphonate

A sample of a 500 TBN sulphonate detergent is prepared using a flangevessel with flange and clip, overhead stirrer with paddle andpolytetrafluoroethylene (PTFE) stirrer gland, Dean Stark trap and doublesurface condenser, a mantle/thermocouple temperature controller system,the equipment from just above the mantle to just below the condenserbeing covered with glass wool. The vessel is charged with 35.1 parts byweight of C16-C24 alkylbenzene sulphonic acid and 31.8 parts by weightof mineral oil (SN 150) and heated to 30° C. The reactor is chargedthrough a port with alcohols containing methanol and a mixture ofiso-butanol/amyl alcohol present at 11.6 parts by weight. The weightratio of methanol to the mixture of iso-butanol/amyl alcohol is 1.31.The reactor is charged with 14.9 parts by weight of calcium hydroxideand the mixture is heated to 54° C. where carbon dioxide is added toform a carbonated product. The carbonated product is further treatedthree more times with similar (or equal) portions of calcium hydroxideand carbon dioxide. Water is removed by stripping before repeating theaddition of alcohol, calcium hydroxide and carbon dioxide 2 times. Theproduct is stripped and filtered.

Reference Examples R1-R7 Reference Example 1 R1

An oil of lubricating viscosity is prepared by blending 80 wt % ofExxon™ 600N oil with 11.9 mm²s⁻¹ (cSt) at 100° C. with 20 wt % of Exxon™150BS oil with 31.7 mm²s⁻¹ (cSt) at 100° C. A commercially availableconventional sulphur containing phenate detergent (“type 1”) and asulphonate detergent with a total base number of 500 are added to theoil of lubricating viscosity on an oil free basis at 4.6 wt % and 12.9wt % respectively. The “sulphur containing phenate detergent (‘type 1’)”has a metal ratio of 8.6:1. The alkylphenol of the sulphur containingphenate oligomer has 22 wt % in the form of the dimer, 23 wt % in theform of the trimer and 46 wt % in the form of the tetramer or higheroligomers.

Reference Example 2 R2

The experimental procedure is identical to the process of ReferenceExample 1, except the phenate detergent is commercially availableconventional sulphur containing phenate detergent (“type 2”). The“sulphur containing phenate detergent type 2” has a metal ratio of7.7:1. The alkylphenol of the sulphur containing phenate oligomer has 22wt % in the form of the dimer, 23 wt % in the form of the trimer and 46wt % in the form of the tetramer or higher oligomers.

Reference Example 3 (R3) The experimental procedure is identical to theprocess of Reference Example 1, except the phenate detergent is added onan oil free basis at 3.08 wt % and the sulphonate is added at 13.33 wt%.

Reference Example 4 R4

The experimental procedure is identical to the process of ReferenceExample 2, except the phenate detergent is added on an oil free basis at3.08 wt % and the sulphonate is added at 13.33 wt %.

Reference Example 5 R5

The experimental procedure is identical to the process of ReferenceExample 1, except a detergent package of a sulphonate with a total basenumber of 400 is on an oil free basis added at 7.5 wt %; and acommercially available phenate detergent with a total base number of 250is added on an oil free basis at 16 wt %. Furthermore the oil oflubricating viscosity contains on an oil free basis a polyisobutylenesuccinimide dispersant at 1.2 wt %.

Reference Example 6 R6

The experimental procedure is identical to the process of ReferenceExample 1, except sulphonate with a total base number of 400 is added onan oil free basis at 1.93 wt %; and a commercially available phenatedetergent with a total base number of 250 is added on an oil free basisat 3.0 wt %.

Reference Example 7 R7

The experimental procedure is identical to the process of ReferenceExample 1, except sulphonate with a total base number of 400 is added onan oil free basis at 3.2 wt %; and a commercially available phenatedetergent with a total base number of 250 is added on an oil free basisat 1.3 wt %.

Reference Examples 8-10

Reference Examples 8 to 10 are believed to be representative ofcommercially available materials containing an oil of lubricatingviscosity and a detergent package (on a oil free basis) of 14.3 wt % of250 TBN overbased phenate and 2.3 wt % of a 400 TBN sulphonate forReference Example 8 (R8); 9.7 wt % of 250 TBN overbased phenate and 4.7wt % of a 400 TBN sulphonate for Reference Example 9 (R9); and 4.8 wt %of 250 TBN overbased phenate and 7.7 wt % of a 400 TBN sulphonate forReference Example 10 (R10).

Reference Example 11

Reference Example 11 is believed to be a commercially available materialcontaining an oil of lubricating viscosity and a detergent package (on aoil free basis) of 1 wt % of 250 TBN overbased phenate and 9 wt % of a400 TBN sulphonate; and an antiwear package containing on a oil freebasis 0.5 wt % of a borated dispersant; 0.22 wt % of a zincdithiophosphate; and 0.25 wt % of a sulphurised olefin.

Example 1 Ex1

The experimental procedure is identical to the process of ReferenceExample 1, except the phenate detergent is a commercially productavailable from The Lubrizol Corporation with a total base number of 150.The phenate detergent has a metal ratio of 1:1. The alkylphenol of thesulphur containing phenate is oligomerised with 13 wt % in the form ofthe dimer, 21 wt % in the form of the trimer and 60 wt % in the form ofthe tetramer or higher oligomers.

Example 2 Ex2

The experimental procedure is identical to the process of ReferenceExample 3, except the phenate detergent is the commercially availableproduct of Ex1 with a total base number of 150.

Example 3 Ex3

The experimental procedure is identical to the process of ReferenceExample 1, except a detergent package of a sulphonate with a total basenumber of 500 is added on an oil free basis at 10.67 wt %; and thecommercially available phenate detergent of Ex1, TBN 150, is added on anoil free basis at 5.56 wt %. Furthermore the oil of lubricatingviscosity contains on an oil free basis a polyisobutylene succinimidedispersant in an amount of 1.2 wt %.

Example 4 Ex4

The experimental procedure is identical to the process of ReferenceExample 3, except the sulphonate with a total base number of 500 isadded on an oil free basis at 9.52 wt % and the commercially availablephenate detergent of Ex 1, TBN 150, is added on an oil free basis at14.93 wt %. Furthermore the oil of lubricating viscosity contains on anoil free basis a polyisobutylene succinimide dispersant at 0.6 wt %.

Example 5 Ex5

The experimental procedure is identical to the process of ReferenceExample 3, except the sulphonate with a total base number of 500 isadded on an oil free basis at 12.66 wt % and the commercially availablephenate detergent of Ex1, TBN 150, is added on an oil free basis at 4.62wt %. Furthermore the oil of lubricating viscosity contains on an oilfree basis a zinc oxide-polyisobutylene succinimide dispersant at 0.81wt %.

Example 6 Ex6

The experimental procedure is identical to the process of ReferenceExample 5, except the sulphonate with a total base number of 500 isadded on an oil free basis at 12.88 wt % and the commercially availablephenate detergent of Ex1, TBN 150, is added on an oil free basis at 3.85wt %.

Example 7 Ex7

The experimental procedure is identical to the process of ReferenceExample 5, except the sulphonate with a total base number of 500 isadded on an oil free basis at 12.33 wt % and the commercially availablephenate detergent of Ex1, TBN 150 is added on an oil free basis at 2.31wt %.

Example 8 Ex8

The experimental procedure is identical to the process of ReferenceExample 5, except the sulphonate with a total base number of 500 isadded on an oil free basis at 13.77 wt % and the commercially availablephenate detergent of Ex1, TBN 150, is added on an oil free basis at 0.77wt %.

Example 9 Ex9

Example 11 is the same as Reference Example 11, except the 250 TBNoverbased phenate has been replaced with 3.4 wt % of the commerciallyavailable phenate detergent of Ex1, TBN 150.

Example 10 Ex10

The experimental procedure is identical to the process of ReferenceExample 1, except a detergent package of a sulphonate with a total basenumber of 500 is added on an oil free basis at 8.8 wt %; and thecommercially available phenate detergent of Ex1, TBN 150 is added on anoil free basis at 4 wt %. Furthermore the oil of lubricating viscositycontains on an oil free basis a non-borated polyisobutylene succinimidedispersant at 0.6 wt %.

Example 11 Ex11

The experimental procedure is identical to the process of ReferenceExample 1, except a detergent package of a sulphonate with a total basenumber of 500 is added on an oil free basis at 8.8 wt %; and thecommercially-available phenate detergent, TBN 150, is added on an oilfree basis at 4 wt %. Furthermore the oil of lubricating viscositycontains on an oil free basis a borated polyisobutylene succinimidedispersant at 0.5 wt %; a zinc dialkyldithiophosphate at 0.23 wt %; anda sulphurised olefin present at 0.25 wt %.

Example 12 Ex12

The experimental procedure is identical to the process of ReferenceExample 1, except a detergent package of a sulphonate with a total basenumber of 500 is added on an oil free basis at 6.4 wt %; and thecommercially-available phenate detergent, TBN 150, is added on an oilfree basis at 1.5 wt %; and an antiwear package containing a borateddispersant is added on an oil free basis at 0.5 wt % and glycerolmonooleate present on an oil free basis at 0.5 wt %.

Example 13 Ex13

The experimental procedure is identical to the process of ReferenceExample 1, except a phosphoric acid ester amine salt is added on an oilfree basis at 0.5 wt %.

Test 1: Pressurised Differential Scanning Calorimetry (PDSC)

Approximately 2.50 mg±0.25 mg of sample is placed in a “TA DSC 2920™Calorimeter,” heated to 215° C. at 40° C. min⁻¹ and held at 690 kPa. Theoxidation induction time for an oil of lubricating viscosity isdetermined by calculating the length of time a heated sample takes tooxidise. The results obtained by testing the lubricants of the indicatedExamples are as shown:

Example PDSC Oxidation Induction Time (mins) R1 35.1 R2 29.5 Ex1 50 R327.1 R4 16.1 Ex2 43

Test 2: Panel Coker

Approximately 233 g of sample is placed in a 250 ml Panel Cokerapparatus and heated to 325° C. The sample is splashed against a metalplate for 15 seconds and then baked for 45 seconds. The splashing andbaking cycle is continued for approximately 3 hours. The sample iscooled to room temperature and the amount of deposits left on the metalplate is weighed. The results obtained by testing the lubricants of theindicated Examples are as shown:

Example Deposits (mg) R1 140 R2 297 Ex1 110 R3 264 R4 353 Ex2 217 R588.3 Ex3 24.9 Ex4 15.4 R6 88.9 Ex5 19.2 Ex6 53.4 R7 334.4 Ex7 112.5 Ex8183.2 R8 63 R9 102 R10 167 Ex9 68 R11 177

Test 3: Cameron Plint of Examples 10 and 11

The Cameron Plint TE-77™ is a reciprocating wear tester. In this test asteel ball upper specimen is reciprocated against a steel flat lowerspecimen. The sample is initially treated with 3.5 wt % sulphuric acid.The Cameron Plint is then charged with 10 ml of the sample and heated to50° C. and held for 20 minutes. The sample is then subject to a load of25 N over two minutes while at the same time the reciprocation isstarted at 10 Hz over 15 mm stroke length. The sample is then heated to350° C. at 2° C. per minute and held for 3 hours. At the end of the testthe Onset of film failure is measured. The mid point of film failure isdetermined by the temperature at which the oil film as measured by thecontact potential, first falls to half of its starting value. Theresults obtained by testing the lubricants of the indicated Examples areas shown:

Example Onset of Film Failure (° C.) Mid-Point of Film Failure (° C.)Ex10 210 245 Ex11 280 315 Ex12 270 295 Ex13 295 300

The analysis of the experimental data obtained for the followingcombinations of reference examples and invention examples R1, R2 withEx3; R1, R4 with Ex2; R5 with Ex3 and Ex4; R6 with Ex5 and Ex6; and R7with Ex7 and Ex8; Ex10 with Ex11; Ex12 and Ex13 shows that overbasedsulphonate detergents used in combination with the sulphur containingphenate detergents of the invention, have improved oil oxidationproperties, reduced wear and less deposit formation than combinations ofoverbased sulphonate detergents and other commercially available sulphurcontaining phenate detergents.

Each of the documents referred to above is incorporated herein byreference. Except in the Examples, or where otherwise explicitlyindicated, all numerical quantities in this description specifyingamounts of materials, reaction conditions, molecular weights, number ofcarbon atoms, and the like, are to be understood as modified by the word“about.” Unless otherwise indicated, each chemical or compositionreferred to herein should be interpreted as being a commercial gradematerial which may contain the isomers, by-products, derivatives, andother such materials which are normally understood to be present in thecommercial grade. However, the amount of each chemical component ispresented exclusive of any solvent or diluent oil, which may becustomarily present in the commercial material, unless otherwiseindicated. It is to be understood that the upper and lower amount,range, and ratio limits set forth herein may be independently combined.Similarly, the ranges and amounts for each element of the invention maybe used together with ranges or amounts for any of the other elements.As used herein, the expression “consisting essentially of” permits theinclusion of substances that do not materially affect the basic andnovel characteristics of the composition under consideration.

As used herein, the term “hydrocarbyl substituent” or “hydrocarbylgroup” is used in its ordinary sense, which is well-known to thoseskilled in the art. Specifically, it refers to a group having a carbonatom directly attached to the remainder of the molecule and havingpredominantly hydrocarbon character. Examples of hydrocarbyl groupsinclude:

hydrocarbon substituents, that is, aliphatic (e.g., alkyl or alkenyl),alicyclic (e.g., cycloalkyl, cycloalkenyl) substituents, and aromatic-,aliphatic-, and alicyclic-substituted aromatic substituents, as well ascyclic substituents wherein the ring is completed through anotherportion of the molecule (e.g., two substituents together form a ring);

substituted hydrocarbon substituents, that is, substituents containingnon-hydrocarbon groups which, in the context of this invention, do notalter the predominantly hydrocarbon nature of the substituent (e.g.,halo (especially chloro and fluoro), hydroxy, alkoxy, mercapto,alkylmercapto, nitro, nitroso, and sulfoxy);

hetero substituents, that is, substituents which, while having apredominantly hydrocarbon character, in the context of this invention,contain other than carbon in a ring or chain otherwise composed ofcarbon atoms. Heteroatoms include sulfur, oxygen, nitrogen, andencompass substituents as pyridyl, furyl, thienyl and imidazolyl. Ingeneral, no more than two, in one aspect no more than one,non-hydrocarbon substituent will be present for every ten carbon atomsin the hydrocarbyl group; typically, there will be no non-hydrocarbonsubstituents in the hydrocarbyl group.

1. A composition comprising: (a). at least about 3 weight percent of anoverbased sulphonate detergent with a metal ratio of about 12.5:1 toabout 40:1; (b). at least about 1.5 weight percent of a sulphurcontaining phenate detergent with a metal ratio of not more than about3; (c). an oil of lubricating viscosity; and (d). an antiwear agentselected from the group consisting of salixarates, fatty amides, aminesalts of phosphoric acid esters, thiocarbamate esters, thiocarbamatesamides, thiocarbamic ethers, alkylene-coupled thiocarbamates,bis(S-alkyldithocarbamyl)disulfides, monoesters of polyols and aliphaticcarboxylic acids, and borate esters, wherein the sulphur containingphenate contains oligomers of hydrocarbyl phenol with at least about 50wt % of said oligomers in the form of the tetramer or higher oligomers.2. The composition of claim 1, wherein the antiwear agent contains anatom of sulphur, phosphorus, boron or mixtures thereof.
 3. Thecomposition of claim 2, wherein the antiwear agent is asulphur-containing thiocarbamate.
 4. The composition of claim 3, whereinthe thiocarbamate is selected from the group consisting of thiocarbamateesters, thiocarbamate amides, thiocarbamic ethers, alkylene-coupledthiocarbamates, and bis(S-alkyldithiocarbamyl) disulfides.
 5. Thecomposition of claim 1, wherein the antiwear agent comprises a monoesterof a polyol and an aliphatic carboxylic acid.
 6. The composition ofclaim 5, wherein the antiwear agent comprises glycerol monooleate. 7.The composition of claim 1 wherein the antiwear agent is an ashlessantiwear agent.
 8. The composition of claim 1, wherein the sulphonatedetergent has a total base number of at least about
 400. 9. Thecomposition of claim 1, wherein the sulphur containing phenate detergentis represented by the formula:

wherein the number of sulphur atoms y is 1 to about 8; T is hydrogen oran (S)_(y) linkage terminating in hydrogen, an ion or a non-phenolichydrocarbyl group sulphur; M is hydrogen, a valence of a metal ion, anammonium ion and mixtures thereof, provided hydrogen is present on lessthan about 30% of the M entities; and R² is hydrogen or hydrocarbylgroups containing about 4 to about 80 carbon atoms; x is 0 to about 10,provided that at least about 50% of x is about 2 or higher; w, is in therange from 0 to about 3, provided that at least one aromatic ringcontains an R² substituent and the total number of carbon atoms in theR² groups is at least about
 8. 10. The composition of claim 1, whereinthe sulphur containing phenate detergent contains less than about 20 wt% dimeric structures.
 11. The composition of claim 1, wherein thesulphur containing phenate detergent contains a substrate levelexcluding metal M and any carbonate of M in the range about 45 to about95 wt % of the sulphur containing phenate detergent.
 12. The compositionof claim 1, wherein the sulphur containing phenate detergent has a totalbase number between about 30 to about
 220. 13. The composition of claim1 further comprising a borated dispersant.
 14. A method for lubricatingan internal combustion engine, comprising supplying thereto a lubricantcomprising the composition of claim
 1. 15. The method of claim 14,wherein the internal combustion engine is a marine diesel engine. 16.The method of claim 15, wherein the internal combustion engine is2-stroke engine.